In an exhaust gas turbocharger which compresses intake air for an engine, particularly an exhaust gas turbocharger for a vehicle engine, a wastegate valve is provided to prevent a supercharging pressure of the intake air from increasing excessively due to increasing pressure of the exhaust gas. The wastegate valve is configured such that the exhaust gas is partially diverted from an inlet side of an exhaust gas path of the turbine housing into an exhaust gas outlet path via an exhaust gas bypass path which is opened and closed by the wastegate valve so as to reduce energy of the exhaust gas supplied to the turbine rotor.
A conventional wastegate valve for an exhaust gas turbocharger is disclosed in Patent Literature 1 and Patent Literature 2.
In the disclosure of Patent Document 1, as shown in FIG. 11, a valving element 02 attached to a tip of an operating lever 01 is moved by turning the operating lever 01 to open and close a path. Further, in Patent Literature 1, a valve stem 03 of the valving element 02 is inserted in an insertion hole 04 of the operating lever 01 and a groove 06 with a whirl stopper face 05 is formed in an opening part of the insertion hole 04 of the operating lever 01. In the groove 06, a whirl stopper washer 07 is fitted such that a lateral face thereof is in contact with the whirl stopper face 05. The washer 07 is fixed to the valve stem 03 by caulking or welding.
In the disclosure of Patent Literature 2, a disc spring 011 shown in FIG. 12A is provided between a valving element and a lever 013, and the disc spring shown in FIG. 12B is provided between the lever 013 and a plate provided on the opposite side of the valving element 012 so as to apply force against the valving element 012. Thus, the valving element 012 is attached to the lever 013 such as to absorb vibration of the valving element 012.